The invention relates to a snow plow.
A snow plow of the general nature of the present invention is disclosed for example, in German Published, Non-examined Patent Application DE-OS 21 45 215. This snow plow has on the back of each blade two lateral curved guides. This curved guidance is intended to assure that, when an obstacle on the ground is encountered, the respective blade is turned out around the center of the curved guidance in respect to the obstacle, the scraping edge driving up against the obstacle first being pivoted towards the back and then being lifted up on the curve of the circle so that the obstacle can be overridden.
The respective blade is maintained and returned into the initial position by a plurality of spring tension devices.
In connection with the foregoing known snow plow, a connection at only a point or line is made because of the specific curved guidance, even if bearing rollers are used. In case of particularly heavy snow removal, however, the forces acting on the supports are strong enough that they result in not inconsiderable damage and disadvantages. Moreover, problems arise in connection with the setting of the restoring force and with the return of the blade into the operational position once it has been deflected. A relatively large pivot path is traversed in the course of the deflection movement of the blade, in the course of which the spring elements, which act on the top of the back of the blade, are stretched over a large travel of the spring. This then means that the restoring force further increases, dependent on the spring travel. A compromise is hard to find in actual use to, on the one hand, be able to set the release forces as high as possible in case of hard removal and, on the other, not to allow the restoring forces, which further increase with the stretching of the restoring springs, to become too great.
It is therefore the object of the present invention to overcome the disadvantages of the state of the art and to further providing an improvement snow plow which affords increased support, and deflection movements without problems throughout the full range of the deflection movement.
A curved slide bearing is used for the first time with the snow plow of the present invention, which results in all-over support and force absorption. Because of this, and especially with heavy removal, the occurring forces can be supported and absorbed without problems and without leading to an impairment of the bearing elements. Because of the additional use of a force limiter it is possible to set the triggering forces without problem when a ground obstacle is encountered. The force limiter has the further considerable advantage that after the triggering forces have been overcome, the characteristic magnitude of force, for all practical purposes, abruptly drops down to another, preset and much lower value in order to perform the pivot movement of the blade to the end without problem after driving up against an obstacle on the ground and overcoming the triggering force. This makes possible a safe crossing over the ground obstacle.
In a particularly preferred embodiment it is of course also possible to provide slide bearings for the lateral support of each one of the blades.
The use of a first curved segment and a second one cooperating with it has proven particularly advantageous. These are designed to interact in the manner of a groove/spring connection and thus are captively guided slidingly in respect to each other. In this way the lateral forces are also being absorbed.
Plastics are particularly suitable as materials for the slide bearing.
In the snow plow of the invention it is possible without problems to change and pre-set the pitch angles of the scraper edge. For this purpose the position of the force limiter, which is supported at least indirectly between one blade and the support frame, can be changed at least at one connecting point, by means of which the angular position of the deflectable blade and thus the pitch angle of a scraper edge are determined. The adjustment can be performed remotely controlled either mechanically or hydraulically, pneumatically or by an electric motor, for example by means of an eccentric, a worm, etc. Mechanical as well as hydraulic or pneumatic designs can be considered as force limiters.
In accordance with an improvement of the invention, a force limiter is used which operates not in the sense of an extension, but in the sense of a shortening when a triggering force takes effect and which for this purpose is preferably disposed in the lower area of the blade. It consists of a connecting link of an elastomeric material which may be in the shape of a strap, for example.
With an appropriate adjustment, maximum triggering forces are generated at the start by means of this connecting link of elastomeric material, the pivoting into a deflection position only being possible when the triggering forces are exceeded. After the triggering forces have been exceeded, here, too, the elastomeric connecting link is being increasingly curved, the forces permitting further deflection of the blade are less by far than the triggering forces to be exceeded at the start.
The direction and place of the curving operation is also determined by the slightly arced curve in the initial position.
Thus the present invention has decisive advantages in comparison with the already known devices. Conventional restoring springs had to be made large and strong. This was necessary to assuredly and quickly return the blade, which was suspended in a curved guide, from its deflection into its scraping position after a deflection maneuver had been performed. Furthermore, it was also necessary to set the desired high triggering forces by means of the restoring springs. Not only were the large size restoring springs expensive, they also have the additional disadvantage that, when the triggering force has been attained, with increased pivoting of the blade into the deflection position the springs are further stretched and thus the resilience which must be overcome in the direction of deflection increases even more.
In contrast thereto, a force limiter is proposed by the design of the invention where the triggering forces can essentially be set independently of a restoring spring device and where it is also assured in a particularly advantageous manner that, when the triggering force has been attained and overcome, the further adjustment movement into the deflection position can take place without problems, because the further adjustment forces to be overcome after exceeding the triggering force do not increase, but diminish rapidly or are kept at a low level.